1. Field of the Invention
The present invention relates to a magnetization apparatus and a magnetization method, and typically relates to a magnetization apparatus and a magnetization method for externally magnetizing a non-magnetized magnetic material, which is provided to an inner periphery of a yoke housing, from an outer peripheral portion of the yoke housing.
2. Description of Related Art
Conventionally, a motor, such as a wiper motor, a window motor, a sunroof motor, and a seat motor, includes a tubular yoke housing with a bottom, a brush holder unit, and a gear housing. The yoke housing rotatably receives an armature such that the armature is rotatable, and the brush holder unit is assembled with a side of the yoke housing toward an opening of the yoke housing (assembled with an opening side of the yoke housing). The gear housing is assembled to the yoke housing through the brush holder unit (see, for example, JP-A-2003-61303, JP-A-2004-503192).
A motor disclosed in JP-A-2003-61303 has a permanent magnet, the armature, and a commutator. The permanent magnet disposed at an inner peripheral surface of the yoke housing. The armature is rotatably received in the yoke housing to oppose the permanent magnet. The commutator is provided on a rotation shaft of the armature toward the opening side of the yoke housing. The brush holder unit includes a brush holder body portion and a connector portion. The connector portion projects outwardly from the brush holder body portion in a radial direction of the rotation shaft. The brush holder body portion supports a brush, which slides on the commutator, in a state, where the brush is biased toward the commutator.
The connector portion is connected with an external connector for power supply to the motor and for sending and receiving signals. The connector portion outwardly extends from the brush holder body portion in the radial direction of the rotation shaft, and the connector portion further projects toward the yoke housing along the axis of the rotation shaft to be positioned on a side of the yoke housing (positioned radially outward of the yoke housing).
When the above motor is manufactured, a premagnetized permanent magnet may be placed inside the yoke housing, and then an armature may be inserted into the yoke housing. In this manufacturing method, a magnetic force of the permanent magnet may attract the armature, and therefore this brings disadvantage, where the armature cannot be assembled smoothly.
In order to handle this disadvantage, firstly a magnetic material (non-magnetized permanent magnet) and the armature are placed inside the yoke housing, and then the magnetic material is magnetized from an outer peripheral portion of the yoke housing by using a magnetization apparatus.
However, a motor disclosed in JP-A-2003-61303 has a connector portion provided radially outward of the yoke housing and the permanent magnet. Therefore, when the magnetic material needs to be magnetized from an outer peripheral portion of the yoke housing after assembling a magnetic material, an armature, and a brush holder unit with the yoke housing, the yoke housing may not be placed between opposing magnetization cores of the magnetization apparatus because the connector portion obstacles. Because of this, after the magnetized permanent magnet is placed to the yoke housing, the armature needs to be inserted into the yoke housing, resulting in that the motor disclosed in JP-A-2003-61303 disadvantageously requires more time (labor) for in the assembly.
Also, in the motor disclosed in JP-A-2003-61303, when the magnetic material is magnetized from an outer periphery of the yoke housing using the magnetization apparatus after the magnetic material, the armature, and the brush holder unit have been assembled, a projection direction of the connector portion may require to be changed, for example, in an opposite direction (a direction opposite the yoke housing). Therefore, a flexibility of designing is limited.
In contrast, in a motor disclosed in JP-A-2004-503192, an intermediate connector portion extends radially outwardly from the brush holder unit, and a separated electronic device casing, which houses a printed board, is assembled to the intermediate connector portion. The electronic device casing has a connector, which is connected with an external connector.
Due to the above structure, in the motor disclosed in JP-A-2004-503192, even after the brush holder unit has been assembled, the magnetic material can be magnetized by placing the yoke housing to the magnetization apparatus only if the electronic device casing has not been attached.
However, in the motor disclosed in JP-A-2004-503192, after the magnetization process, the separated electronic device casing requires to be assembled. Thus, a component count becomes disadvantageously larger. Also at the same time, because the intermediate connector portion and the electronic device casing are electrically connected while the electronic device casing is supported in the above structure, the supporting performance of this connection becomes smaller. Therefore, another structure for supporting the electronic device casing is required other than the connection. As a result, the motor disadvantageously becomes larger in size.